7 Exposure to Volatile Organic Compounds Lance A Wallace U.S Environmental Protection Agency (ret.) Sydney M Gordon Battelle Memorial Institute CONTENTS 7.1 7.2 7.3 Synopsis 147 Introduction 148 Human Exposure 150 7.3.1 Air .150 7.3.1.1 Benzene .154 7.3.1.2 para-Dichlorobenzene .155 7.3.1.3 Tetrachloroethylene 156 7.3.1.4 Carbon Tetrachloride .157 7.3.1.5 Formaldehyde 157 7.3.1.6 1,3-Butadiene 157 7.3.2 Drinking Water 158 7.4 Discussion 158 7.5 Conclusion 159 7.6 Appendix — Measurement Methods 160 7.6.1 Air .160 7.6.1.1 Air Sampling .160 7.6.1.2 Analysis .163 7.6.1.3 Real-Time (Simultaneous Sampling and Analysis) Techniques 163 7.6.2 Body Fluids 165 7.6.2.1 Breath 165 7.6.2.2 Blood 166 7.6.2.3 Urine 167 7.7 Questions for Review 167 References 168 7.1 SYNOPSIS Volatile organic compounds (VOCs) surround us at all hours of the day Each breath we take contains some hundreds of these compounds, many of which our bodies must metabolize or excrete to remain healthy Both outdoor and indoor sources contribute to our exposure, but for a large percentage of these compounds, it is a small indoor or personal source right under our nose that 147 © 2007 by Taylor & Francis Group, LLC 148 Exposure Analysis is the largest contributor These facts were first demonstrated on a large national scale by the Total Exposure Assessment Methodology (TEAM) studies of the early 1980s, and this historical effort is described below The TEAM studies benefited from the availability of new sorbents, stronger batteries, and miniaturized pumps to allow small personal monitors to measure 12-hour exposures to a target list of some 32 VOCs Because of the extraordinarily small concentrations of most VOCs, methods of sampling and analysis have had to meet extraordinary demands for sensitivity and stability Progress in developing such methods is continuing today, and this chapter provides a very thorough coverage of these methods VOCs generally “prefer” to be in the air, but can also be found in drinking water and in our bodies (breath, blood, urine, and fat cells, particularly breast milk) A large number of studies of VOC concentrations outdoors, indoors, and in these biological media are discussed Major sources of VOCs (automobile exhaust, secondhand smoke, building materials, consumer products, chlorinated water, air fresheners) are identified and several individual VOCs with the greatest cancer risk are characterized in full: benzene, chloroform, para-dichlorobenzene, formaldehyde, tetrachloroethylene, and carbon tetrachloride Less frightening but possibly causing far more economic harm is the apparent involvement of VOCs in reducing worker productivity through eye, nose, and throat irritation, headaches, and other apparently “minor” but debilitating symptoms Sometimes these symptoms escalate into full-blown syndromes such as sick building syndrome (SBS) or multiple chemical sensitivity (MCS), although the involvement of VOCs has not been proven due to the lack of adequate double-blind studies 7.2 INTRODUCTION Volatile organic compounds (VOCs) comprise some thousands of chemicals, many of which are in wide use as paints, adhesives, solvents, fragrances, and other ingredients in processes and consumer products (Table 7.1) VOCs have great economic importance Many chemicals with the highest annual production figures are VOCs They also sometimes occur as unwanted ingredients or impurities — for example, benzene in gasoline, or formaldehyde in pressed wood products As their name implies, VOCs are so volatile that under normal conditions they are found overwhelmingly in the gaseous state They may occur in liquids, often volatilizing from those liquids when given the chance (for example, chloroform from treated water, methyl tert-butyl [MTBE] from groundwater) They may also be in the form of solids (e.g., naphthalene and paradichlorobenzene, used as mothballs and bathroom deodorants) that sublime (go from solid to gas without an intervening liquid stage) at room temperature Human exposure to most VOCs is mainly through inhalation; a small number of VOCs are in drinking water as contaminants Some VOCs may travel in groundwater or through soil from hazardous waste sites, landfills, or gasoline spills to inhabited areas Two main health effects are of interest: cancer and acute irritative effects (eye, nose, throat, and skin irritation, headaches, difficulty concentrating, etc.) The latter may have a greater economic effect than the former because of reduced productivity of workers (Fisk and Rosenfeld 1997) Some VOCs are considered to be human carcinogens (benzene, vinyl chloride, formaldehyde) Others are known animal carcinogens and may be human carcinogens (methylene chloride, trichloroethylene, tetrachloroethylene, chloroform, p-dichlorobenzene, 1,3-butadiene) Others are mutagens (α−pinene) or weak animal carcinogens (limonene) Many common VOCs have well-documented health effects, often neurobehavioral, at high (occupational) concentrations A recent study of benzene exposures in the shoemaking industry in China showed clear reductions in white blood cells even for the lowest exposures (about 0.57 ppm), well under the U.S occupational standard of ppm (Lan, Zhang, and Li 2004) Acute effects at lower environmental concentrations are often difficult to observe under controlled conditions, although Mølhave and coworkers (Mølhave and Møller 1979; Mølhave 1982, 1986; Mølhave, Bach, and Pedersen 1984, 1986) were able to observe some subjective effects such as reported headache © 2007 by Taylor & Francis Group, LLC Exposure to Volatile Organic Compounds 149 TABLE 7.1 Common Volatile Organic Chemicals and Their Sources Chemicals Acetone Alcohols (ethanol, isopropanol) Aromatic hydrocarbons (toluene, xylenes, ethylbenzene, trimethylbenzenes) Aliphatic hydrocarbons (octane, decane, undecane) Benzene Butylated hydroxytoluene (BHT) Carbon tetrachloride Chloroform p-Dichlorobenzene Ethylene glycol, Texanol Formaldehyde Furfural Methylene chloride Methyl-tert-butyl ether (MTBE) Phenol Styrene Terpenes (limonene, α-pinene) Tetrachloroethylene Tetrahydrofuran 1,1,1-Trichloroethane Trichloroethylene Major Sources of Exposure Cosmetics Spirits, cleansers Paints, adhesives, gasoline, combustion sources Paints, adhesives, gasoline, combustion sources Smoking, auto exhaust, passive smoking, driving, refueling automobiles, parking garages Urethane-based carpet cushions Fungicides, global background Showering, washing clothes, dishes Room deodorizers, moth cakes Paints Pressed wood products Cork parquet flooring Paint stripping, solvent use Gasoline, groundwater contaminant Vinyl flooring, cork parquet flooring Smoking Scented deodorizers, polishes, cigarettes, food, beverages, fabrics, fabric softeners Wearing/storing dry-cleaned clothes Sealer for vinyl flooring Aerosol sprays, solvents, many consumer products Cosmetics, electronic parts, correction fluid using a mixture of 22 common VOCs at a total concentration of mg/m3, which is high but is sometimes encountered in new or renovated buildings The U.S Environmental Protection Agency (USEPA) later confirmed these findings (Otto et al 1990) Irritation from VOCs is thought to be mediated through the trigeminal nerve, or “common chemical sense” (Bryant and Silver 2000; Cometto-Muñiz 2001) Despite the difficulty of observing effects under controlled conditions, a very common worldwide phenomenon is reported increases in symptoms of large numbers of workers following occupation of a new or renovated building (Berglund, Berglund, and Lindvall 1984; Sundell et al 1990; Preller et al 1990) This phenomenon has come to be known as sick building syndrome (SBS) and is characterized by multiple symptoms: eye irritation, stuffy nose, sore throat, headaches, skin rashes, and difficulty concentrating (Mølhave 1987; Ten Brinke et al 1998) Since such new or renovated buildings almost always have very high levels of VOCs for a period of months or more after completion, SBS has been thought to be a possible effect of VOC exposure A similar, more serious, syndrome, multiple chemical sensitivity (MCS), has also been suggested to be a result of VOC or pesticide exposure, either chronic or following a single massive dose A comprehensive review of MCS is found in Ashford and Miller (1997) The International Programme on Chemical Safety (IPCS) has recommended double-blind controlled chamber studies to determine if symptoms can be reproducibly created by exposures to VOCs (IPCS 1996) Although several such studies have been carried out, results are mixed (Fiedler and Kipen 2001) A recent © 2007 by Taylor & Francis Group, LLC 150 Exposure Analysis study (Joffres, Sampalli, and Fox 2005) determined that sensitive patients take longer to adapt to the conditions prior to the testing, which may account for some of the negative findings A less serious but possibly very costly result of VOC exposure may be reduced productivity resulting from minor ailments such as headache and eye irritation The total annual cost of poor indoor air quality has been estimated to be in the neighborhood of 100 billion dollars (Fisk and Rosenfeld 1997) This chapter concentrates on exposure in air, with a brief discussion of exposure in drinking water VOCs can also be absorbed through the skin, and this is the subject of a separate chapter on dermal exposure from baths and showers Because of the crucial importance of measurement methods in detecting low-level VOCs, there is an Appendix on measurement methods in air, water, and biological media (breath, blood, urine) Since new methods are often developed and described as part of studies of human exposure, such exposure studies are also described and referenced in this Appendix when appropriate 7.3 HUMAN EXPOSURE 7.3.1 AIR Between 1979 and 1987, the USEPA carried out the TEAM studies to measure personal exposures of the general public to VOCs in several geographic areas in the United States (Pellizzari et al 1987a,b; Wallace 1987) About 20 target VOCS were included in the studies, which involved about 750 persons, representing 750,000 residents of the areas Each participant carried a personal air quality monitor containing 1.5 g Tenax A small battery-powered pump pulled about 20 L of air across the sorbent over a 12-hour period Two consecutive 12-hour personal air samples were collected for each person Concurrent outdoor air samples were also collected in the participants’ backyards In the studies of 1987, fixed indoor air samplers were also installed in the living rooms of the homes The initial TEAM pilot study (Wallace et al 1982) in Beaumont, TX, and Chapel Hill, NC, indicated that personal exposures to about a dozen VOCs exceeded outdoor air levels, even though Beaumont, TX, has major oil producing, refining, and storage facilities These findings were supported by a second pilot study in Bayonne–Elizabeth, NJ (another major chemical manufacturing and petroleum refining area) and Research Triangle Park, NC (Wallace et al 1984a) A succeeding major study of 350 persons in Bayonne–Elizabeth (Wallace et al 1984b) and an additional 50 persons in a nonindustrial city and a rural area (Wallace et al 1987a) reinforced these findings A second major study in Los Angeles, CA, and in Antioch–Pittsburg, CA (Wallace et al 1988) with a follow-up study in Los Angeles in 1987 (Wallace et al 1991a) added a number of VOCs to the list of target chemicals with similar results Major findings of these TEAM studies included the following: • • • Personal exposures exceeded median outdoor air concentrations by factors of to for nearly all prevalent VOCs The difference was even larger (factors of 10 or 20) when the maximum values were compared, despite the fact that most of the outdoor samples were collected in areas with heavy industry (New Jersey) or heavy traffic (Los Angeles) Major sources are consumer products (bathroom deodorizers, moth repellents); personal activities (smoking, driving); and building materials (paints and adhesives) In the United States, one chemical (carbon tetrachloride) has been banned from consumer products and exposure is thus limited to the global background of about 0.7 µg/m3 Traditional sources (automobiles, industry, petrochemical plants) contributed only 20–25% of total exposure to most of the target VOCs (Wallace 1987) No difference in exposure was noted for persons living close to chemical manufacturing plants or petroleum refineries © 2007 by Taylor & Francis Group, LLC Exposure to Volatile Organic Compounds 151 A more recent study of personal exposure to VOCs was carried out on 450 persons in six cities in Europe as part of the EXPOLIS study (Saarela et al 2003, Edwards et al 2005) In every city, indoor home VOC concentrations were greater than outdoor levels, with ratios generally ranging from to Personal exposures were also greater than indoor air levels for some compounds, particularly aromatics and alkanes, leading the authors to posit exposures in traffic as likely contributors The most common VOCs included toluene and xylenes among the aromatics and limonene and α-pinene among the terpenes, similar to most other studies Son, Breysse, and Yang (2003) used passive badges to measure personal, indoor, and outdoor concentrations of 10 target VOCs for 30 persons in Seoul, South Korea, and 30 in a smaller city of Asan Average indoor, outdoor, and personal exposures to benzene in Asan were 20–23 µg/m3, and 40–43 µg/m3 in Seoul These are several times higher than in the United States Benzene levels were increased in homes with smoking and homes that used mosquito coils (incense) A “new” VOC of considerable interest and concern has arisen as a result of attempts to reduce the carbon monoxide emitted from incomplete combustion in automobiles To improve combustion, oxidizers are required to be added to gasoline in some areas of the United States One of the most popular of these is methyl-tert-butyl ether (MTBE), added to gasoline in amounts as high as 17% MTBE appears to have some serious toxic effects, and complaints have been received from residents of some (but not all) of the areas where it has been added to gasoline Additionally, enough time has passed for it to have become one of the most common contaminants of groundwater Several studies have documented the human exposure resulting from refueling autos (Lindstrom and Pleil 1996, Lioy et al 1994) Based on these findings, the USEPA recently banned MTBE as a gasoline additive Three large studies of VOCs, involving 300–800 homes, were carried out in the 1980s in the Netherlands (Lebret et al 1986), West Germany (Krause et al 1987) and the United States (Wallace 1987) Observed concentrations were remarkably similar for most chemicals, indicating similar sources in these countries One exception is chloroform, present at typical levels of 1–4 µg/m3 in the United States but not found in European homes This is to be expected, since the likely source is volatilization from chlorinated water (Wallace et al 1982; Andelman,1985a,b); the two European countries not chlorinate their water Major findings of these indoor air studies include the following: • • • • Indoor levels in homes and older buildings (>1 year) are typically several times higher than outdoor levels Sources include dry-cleaned clothes, cosmetics, air fresheners, and cleaning materials New buildings (